void TriContourGenerator::find_boundary_lines(Contour& contour,
const double& level)
{
// Traverse boundaries to find starting points for all contour lines that
// intersect the boundaries. For each starting point found, follow the
// line to its end before continuing.
const Triangulation& triang = get_triangulation();
const Boundaries& boundaries = get_boundaries();
for (Boundaries::const_iterator it = boundaries.begin();
it != boundaries.end(); ++it) {
const Boundary& boundary = *it;
bool startAbove, endAbove = false;
for (Boundary::const_iterator itb = boundary.begin();
itb != boundary.end(); ++itb) {
if (itb == boundary.begin())
startAbove = get_z(triang.get_triangle_point(*itb)) >= level;
else
startAbove = endAbove;
endAbove = get_z(triang.get_triangle_point(itb->tri,
(itb->edge+1)%3)) >= level;
if (startAbove && !endAbove) {
// This boundary edge is the start point for a contour line,
// so follow the line.
contour.push_back(ContourLine());
ContourLine& contour_line = contour.back();
TriEdge tri_edge = *itb;
follow_interior(contour_line, tri_edge, true, level, false);
}
}
}
}
void TriContourGenerator::find_interior_lines(Contour& contour,
const double& level,
bool on_upper,
bool filled)
{
const Triangulation& triang = get_triangulation();
int ntri = triang.get_ntri();
for (int tri = 0; tri < ntri; ++tri) {
int visited_index = (on_upper ? tri+ntri : tri);
if (_interior_visited[visited_index] || triang.is_masked(tri))
continue; // Triangle has already been visited or is masked.
_interior_visited[visited_index] = true;
// Determine edge via which to leave this triangle.
int edge = get_exit_edge(tri, level, on_upper);
assert(edge >= -1 && edge < 3 && "Invalid exit edge");
if (edge == -1)
continue; // Contour does not pass through this triangle.
// Found start of new contour line loop.
contour.push_back(ContourLine());
ContourLine& contour_line = contour.back();
TriEdge tri_edge = triang.get_neighbor_edge(tri, edge);
follow_interior(contour_line, tri_edge, false, level, on_upper);
if (!filled)
// Non-filled contour lines must be closed.
contour_line.push_back(contour_line.front());
else if (contour_line.size() > 1 &&
contour_line.front() == contour_line.back())
// Filled contour lines must not have same first and last points.
contour_line.pop_back();
}
}
void TriContourGenerator::find_boundary_lines_filled(Contour& contour,
const double& lower_level,
const double& upper_level)
{
// Traverse boundaries to find starting points for all contour lines that
// intersect the boundaries. For each starting point found, follow the
// line to its end before continuing.
const Triangulation& triang = get_triangulation();
const Boundaries& boundaries = get_boundaries();
for (Boundaries::size_type i = 0; i < boundaries.size(); ++i) {
const Boundary& boundary = boundaries[i];
for (Boundary::size_type j = 0; j < boundary.size(); ++j) {
if (!_boundaries_visited[i][j]) {
// z values of start and end of this boundary edge.
double z_start = get_z(triang.get_triangle_point(boundary[j]));
double z_end = get_z(triang.get_triangle_point(
boundary[j].tri, (boundary[j].edge+1)%3));
// Does this boundary edge's z increase through upper level
// and/or decrease through lower level?
bool incr_upper = (z_start < upper_level && z_end >= upper_level);
bool decr_lower = (z_start >= lower_level && z_end < lower_level);
if (decr_lower || incr_upper) {
// Start point for contour line, so follow it.
contour.push_back(ContourLine());
ContourLine& contour_line = contour.back();
TriEdge start_tri_edge = boundary[j];
TriEdge tri_edge = start_tri_edge;
// Traverse interior and boundaries until return to start.
bool on_upper = incr_upper;
do {
follow_interior(contour_line, tri_edge, true,
on_upper ? upper_level : lower_level, on_upper);
on_upper = follow_boundary(contour_line, tri_edge,
lower_level, upper_level, on_upper);
} while (tri_edge != start_tri_edge);
// Filled contour lines must not have same first and last
// points.
if (contour_line.size() > 1 &&
contour_line.front() == contour_line.back())
contour_line.pop_back();
}
}
}
}
// Add full boundaries that lie between the lower and upper levels. These
// are boundaries that have not been touched by an internal contour line
// which are stored in _boundaries_used.
for (Boundaries::size_type i = 0; i < boundaries.size(); ++i) {
if (!_boundaries_used[i]) {
const Boundary& boundary = boundaries[i];
double z = get_z(triang.get_triangle_point(boundary[0]));
if (z >= lower_level && z < upper_level) {
contour.push_back(ContourLine());
ContourLine& contour_line = contour.back();
for (Boundary::size_type j = 0; j < boundary.size(); ++j)
contour_line.push_back(triang.get_point_coords(
triang.get_triangle_point(boundary[j])));
}
}
}
}